Engine dying after warm-up

[Don Fitzpatrick]

I have replaced my '79 Universal 5411 with an '88 M-18. I've replaced all exhaust hoses, fuel lines, added a Racor filter and the engine runs like a charm ... for about an hour - then dies like it's run out of fuel. I've checked the hose clamps, all fuel lines , both filters and the fuel pump for air leaks. It could be something else, but I'm curious why the engine would run like a charm (both idle and under load) for about an hour and then die?? The engine temp is fine, as is the oil level and coolant. Bad fuel?? Any ideas? I hope so.

 

[Pete]

out of fuel?

you said that it dies "like it is out of fuel" Is it out of fuel? check the fuel pick up, some how if it is a fuel problem like running out of fuel it is getting air in the system or possible a bad fuel transfer pump. Let us know what the final cure turns out to be Good Luck!

 

[Mark Johnson]

Had the same problem...

and it turned out to be the pickup tube was getting clogged with sludge and algae. I had the tank cleaned out and it ran fine from then on. BTW..very important...always add Biobor or some other type of additive to the fuel each time you fuel up to prevent algae from growing inside your tank. I've been adding Biobor to the fuel for almost 20 years and have never had an algae problem since.

 

[Don Fitzpatrick]

Solved - maybe ??

After hooking up clear hose between the tank and primary filter I noticed some debris, but it did not seem to move toward the pump. Anyway, there was no air but the only time I noticed fuel moving was when I bled the air out from the secondary filter vent.I then disassembled the 12V fuel pump and found that the rubber bellows was torn in several spots ( should have been the first thing to check). My theory is that once the pump heated up the rubber expanded passing less and less fuel. I replaced it with a new one (Napa universal fuel pump) and the engine stalled after twenty minutes. I bled again and it ran until I stopped it 2 hours later. Then restarted up again ( all other times I had to bleed it befor it would start)I think one problem is fixed, but it stalling with the new pump may be from that debris in the fuel.If it stalls again I'll have the tank emptied and cleaned.

 

[Bill Murray]

similar problem

I had the same problem with my 1995 Hunter 29.5 hull # 175.What I finally discovered, after several dangerous situations caused by this problem including being stranded on rocks was a design defect that resulted in a constricted fuel flow and delivery top the engine.After trying everything that everyone recommended, I decided to completely clean out and inspect the entire fuel system from beginning to end. This seemed pretty drastic for an almost brand new boat but I was desperate.I drained all the fuel from the tank using a small pump, and then removed the bulkhead panels in the aft portion of the aft berth and proceeded to remove the fuel tank.This was amazingly easy. Hunter did a great job at designing this part of the boat. Just disconect the fuel lines and fittings, cut the hold down strapping material, and the tank will slide right out of the space it is in. I then removed the pick up tube from the tank and discovered the problem.A screen had been installed on the bottom of the pick up tube. it was installed so that it was folded over the bottom of the pick up tube opening and had been soldered or glued together. The result was that the tube was almost completely closed. Since this engine uses very small amounts of fuel, it ran fine at slow speeds. I also discovered plastic "sawdust" in the tank from the drilling operations to install the fittings. Evidently, when the engine was revved up, suction increased and a very small amount of this plastic plugged the remaining small openings in the screen thus choking off the fuel. When teh engine used all teh fuel in the system it could, it stalled. After a few minutes, with the suction released, the holes opened, and the engine would run fine again, until the cycle repeated.After consulting with some mechanics, I decided to remove the screen completely - after all that is why there are both primary and secondary filters built into the system! Plus, any continued future problems could then be dealt with at the primary filter which would not require removing the tank.I replaced the tank, added new strapping and connected the lines. I have never had any problem at all with theis system in the last 4 years.Good luck with your repair. i would be curious to know what you eventually find.Bill Murray